They say you learn something new every day.

There’s a couple of projects I’ve been working on that I thought were going to be really easy and were actually incredibly difficult. I’ve realised, there are so often so many unforseen circumstances.

I’ve realised that even though I’d read Jeff’s article on estimating before, I’m still rubbish at estimating how long things will take:

When you compare the original single-point estimates to the Best Case and Worst Case estimates, you see that the 11.25 total of the single-point estimates is much closer to the Best Case estimate of 10.5 days than to the Worst Case total of 18.25 days.

You’ll also notice that both the Best Case and Worst Case estimates are higher than the original single-point estimate. Thinking through the worst case result can sometimes expose additional work that must be done even in the best case, which can raise the nominal estimate. In thinking through the worst case, I like to ask developers how long the task would take if everything went wrong. People’s worst case estimates are often optimistic worst cases rather than true worst cases.

I need to start doing this in my projects, and, also, asking other people to do this as well.

I had to get angry with our outsourced IT partner this week as they came to a meeting having not done the one thing I asked them to do. I think I got the balance right – calm but very displeased. So we’ll see if they do it again.

Afterwards, they were so eager to please me that they said they’d get the next bit of work done within a week. I probably should have pushed more for best case/worst case estimates.

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Comments on: "Never underestimate (25/01/2012)" (1)

  1. Estimating is hard. What I tend to do is outlined in this blog post –
    http://use-cases.org/2011/06/04/getting-good-estimates/

    I tend to not use estimation as a pure analytical exercise, but rather a discovery process for risks. The risks that aren’t discovered are the ones that make an optimistic estimate become a late delivery. The important part is the discussion of what could go wrong to make the estimate longer. That’s where I tend to get engineers to dwell.

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